class: center, middle, inverse, title-slide # Raster GIS Overview --- layout: true <div class="dk-footer"> <span> <a href="https://rfortherestofus.com/" target="_blank">R for the Rest of Us </a> </span> </div> --- class: center, middle, dk-section-title background-image:url("https://images.pexels.com/photos/347143/pexels-photo-347143.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260") # Raster GIS Overview ??? --- ## Why do we have two GIS formats? .pull-left[ Vector GIS datasets usually contain sociopolitical data. Vector formats make sense because human locations are vectors: - Country, county and city borders - Roads, airline routes and bike lanes - Physical addresses ] -- .pull-right[ Raster GIS datasets usually contain physical data. Raster formats are a **consequence** of how the data is collected: - Satellite imagery - Weather stations - Road side air quality measurements ] ??? --- ### Do I have vector or raster GIS data? .pull-left[ <img src='images/gg_brexit_by_authority.png' width='400px'/> ] .pull-right[ <img src='images/gg_uk_max_temp.png' width='400px'/> ] ??? --- ## GIS raster layers GIS raster datasets can contain multiple layers. .pull-left[ <img src='images/single-layer-raster.png' width='200px' ALIGN="right"/> For **single** layer raster datasets use these packages: - `{raster}` - `{terra}` ] .pull-right[ <img src='images/raster-data-cube.png' width='200px' ALIGN="right"/> For raster datasets containing **multiple** layers use the `{stars}` package. ] ??? --- ### Why would my data contain multiple layers? <img src='images/landsat-logo.png' ALIGN="left" width='150px' style='margin-right:20px'/> The Landsat program has been continuously studying observing Earth from space since 1972. We'll be using data from the Landsat 7 satellite multiple times in this course. -- All Landsat satellites collects raster data with multiple layers because: -- - they survey the same areas **over time**. -- - they're equipped with **multiple sensors** -- - sensors typically collect data at **multiple wavelength bands** ??? --- ### Raster data cubes Data cubes are raster datasets with 3 dimensions. .pull-left[ <img src='images/raster-data-cube.png'/> ] .pull-right[ All satellite data has at least 3 dimensions: - longitude - latitude - time ] ??? --- ### Hypercubes and higher dimensional raster data Hypercubes are 4-dimensional datasets... but often raster GIS datasets have even more dimensions. .pull-left[ <img src='images/raster-hypercube.png'/> ] .pull-right[ This hypercube is from Landsat 7 and contains the following dimensions: - longitude - latiutude - time - wavelength band ] ??? --- ### Raster data cubes .pull-left[ <img src='images/gg_landsat7_explainer.png'/> ] .pull-right[ This is another view of a data cube from Landsat 7. The dimensions of this data cube are: - longitude - latitude - wavelength band ] ???